Chemical treatment in the manu



' Feb; 25, 19451.V 1 B. RODENB'ERG CHEMICAL TREATMENT IN THE MANUFACTURE0F ETI-[YL ALCOHOL original Filed May 9, 1953' JLOP TOJEWE? BEE?? JOPTOR/46E Ressued Feb. 25,1941

PATENT OFFICE CHEMICAL TREATMENT 1N THE MANU- FACTURE oF ETHYL Amonoi.

Louis B. Rodenberg, Wyoming, Ohio, assignor to National DistillersProducts Corporation, New York, N. Y., a corporation ot VirginiaOriginal No. 2,207,111, dated July 9, 1940, Serial No. 206,871, May 9,1938. Application for reissue December 26, 1940, Serial No. 371,849

5 Claims.

This invention relates to improvements in the continuous distillation ofethyl alcohol, particularly for beverage purposes. It relates moreparticularly to improvements in continuous distil- 5 lation operationswhich enable the production of a product containing radically lessorganic acids and esters than do products normally obtained.

In the manufacture of alcoholic spirits, it is common practice toproduce a beer `containing a relatively small proportion of alcohol by afermentationprocess, and to subsequently concentrate and purify th`ealcohol by distillation, either by batch operations or by continuousdistillation processes. It has long been known that in the production ofsuch spirits, by processes involving either batch or continuousdistillation, the 4presence of appreciable quantities oi.' organic acidsor esters in the final product is objectionable. More or lesssatisfactory methable materials in the ilnal 'product where thedistillation is carried out in batch operations, have been developed;but so far as I am aware, no satisfactory method has been found tosufllciently minimize the quantities of these materials in the nalproduct in the processes involving continuous distillation. Thisdifllculty is due mainly to the -fact that the esters have a boilingpoint very close to that of the alcohol,

which makes their separation in -a continuous distillation unit, such asan alcohol column, very diilicult.

The present invention relates to improvements in the continuousdistillation and rectification in the content oi the objectionableesters and organic acids in the nal product without introducing anydeleterious materials or causing reactions to take place in the materialbeing distilled which might result in the liberation of deleteriousmaterials or compounds.

It has long been known that in the batch distillation of potablespirits, the content ofesters or organic acids Vin the inal product maybe greatly reduced by the addition of alkali to the material beingdistilled; but such addition of alkali has heretofore been subject tothe disadvantage that it has resulted in the liberation of volatilenitrogenous compounds, which Arender a large proportion of thedistillate unfit for beverage purposes due to disagreeable odors andtaste.

For a clearer understanding of the invention, vreference may be had tothe accompanying drawing in which, Figure l is a ilow4 diagram of theods of reducing the quantity of these objection,

of the spirits which permit a radicalA reduction (o1. zoal-57) apparatusemployed in carrying out the process.

In the 'production of ethyl alcohol by continuous distillation, theliquor which is stored in tank III is piped tothe beer distillationcolumn II where it is subjected -to steam distillation. 5 The resultingvapors containing alcohol are conducted through the pipes I2 to thealdehyde column I3. In the aldehyde column the low boiling pointimpurities, such as aldehydes or the like, are volatilized and removedas the liquor i0 ows down thecolumn. The volatilized impurities arecarried off at I4 in the top of the aldehyde column. The partiallypurified product drawn from the bottom at I5 of the aldehyde column isthen introduced into the alcohol coll5 umn I6 where it is distilled andrectied. The liquor in the alcohol column is heated and the resultingvapors proceed upward in the column.

A hot condensate of Ithese vapors is tapped from a plate near'the top ofthe column and consti- 20 tutes the spirits which may be used forpotable or other purposes, and stored in tank I1.

When this process is carried out in accordance with the known practice,the nal product generally 'contains a relatively large amount of 25esters and organic acids, which are highly objectionable if the productis intended for beverage purposes. These objectionable materials cannotbe readily removed by further distillation, because the esters haveboiling points very close to 30 that of the alcohol.

In accordance with the present invention, the continuous distillation iscarried out in the usual manner, except that a suitable basic materialis introduced in ycontrolled amounts to the mate- 35 rial in thealdehyde column, to saponifythe esters and to neutralize the organicacids, Ordinar-ily, the concentration of esters in the aldehyde column.is greatest at the platesl located about at the middle of the upperhalf of this 40 column, shown in Figure l at I9. The basic materialwhich is mlxed in the mixing tank 20 is conducted to the aldehyde columnthrough the conduit 2I, and there mixes with the liquid nowing down-through the aldehyde column. The 45. Yliquid'from which the volatilematerials have been removed during passage down the aldehyde column iscontinually tested for acidity at I5 where itis discharged from the baseof the aldehyde column. The amount of basic material 50 entering thealdehyde column at I9 is regulated in accordancewith the pH value of thedischarge at I5, and it is found that to maintain. the pH value of6.4-6.5 is most advantageous.

In accordance with the present invention, the

the organic acids. Ordinarily, the concentration of esters in thealdehyde column is greatest at the plates located about at the middle ofthe upper half of this column; and the basic material .is advantageouslyadded at this point.

'I'he amount of reagent added must be carefully controlled, and must notbe sufficient to cause the alcohol drawn from the bottom of thealdehydel column to have an alkaline reaction. The reagent saponiflesthe esters and neutralizes the acids at the point of introduction, withthe production of the corresponding salts of the acids, free andcombined. -These salts, and any excess of the basic material, beingnon-volatile, pass down the column, the excess of reagent beingneutralized in saponifying esters present in the lower portions of thecolumn, or by reaction with acids present in the lower portions of thecolumn.

The amount of the basic material added shouldl be such that the productwithdrawn from the bottom of the column has a slightly acid reaction, asif it has an alkaline reaction, volatile nitrogenous compounds may beformed which contaminate the nal product from the alcohol column.Further, if the product taken from the bottom of the aldehyde column isalkaline in reaction, highly objectionable foaming, which interfereswith operation, occurs inthe alcohol column.

'I'he control of the addition of the basic material may be accomplishedin various ways. In general, the amount added should be so controlledthat the material discharged from the bottom of the aldehyde column hasa pH slightly below 7.0,

for example, a'bout 6.5. This may be. accomplished by taking samples ofYthe discharge from time to time and measuring its pH value by anysuitable method, as by a potentiometer. Advantageously, the control ofthe addition of the basic material is automatic, as yby the use of acontinuous potentiometer operating to control the addition so that thepH of the discharge is continuously maintained in the neighborhood ofabout 6.4 to 6.5; that is, slightly below 7.0. With the addition of suchcontrolled amounts of the basic material to the upper part of thealdehyde column, the major portion of the esters are saponifled and themajor portion ofthe organic acids are neutralized so that both areeffectively removed from the nal product. v

Various basic materials may be used in carrying out the process of theinvention, including the alkali metal hydroxides and the carbonatedalkalies, such as sodium and potassium carbonates.

They lare advantageously added in aqueuos solution. The advantages ofthe present invention are illustrated by the following example:

A continuous alcohol distillation unit was operated on productionschedule in accordance with common practice, the alcohol being distilledfrom thbeer in a continuous beer still, the resulting concentrated andpartially purified alcohol being' passed through an aldehyde column,with introduction oi the product, from which the more volatile materialshad been removed in the aldehyde column, into an alcohol column forrectification and purification. The Iinished product contained 1.2 gramsof organic acids and 2.9 grams of esters per hundred liters of liquid.'Ihe pH continuous distillation is carried out in the usual manner,except that a suitable basic material is addedk in controlled amounts tothe aldehyde column, to saponify the esters and to neutralize i value ofthe discharge from the base of the aldehyde column was about 4.4.

The operation was modied by the introduction into the aldehyde column ata point about mid- Way in the upper half of the column of suilicientsodium hydroxide solution to raise the pH of the discharge to about 6.4to 6.5. With such operation, the material entering the alcohol columncontained but a trace of neutralizable and saponiable constituents andthe nal product obtained contained about 1.2 grams of acids per 100liters and substantially no esters. The product obtained Without the useof the sodium hydroxide was decidedly objectionable organoleptivcallybecause of its content of esters, whereas the product yobtained when thesodium hydroxide was introduced into the aldehyde column was ofexcellent quality.

I claim:

1.In a process for producing ethyl alcohol in which a beer containing arelatively small proportion of alcohol is produced by fermentation anddistilled to produce an alcoholic product, the alcoholic product passedrthrough an aldehyde column to remove low-boiling impurities, and thealcoholic liquor discharged from vthe aldehyde column is distilledandrectiiied in an alcohol still; the improvement which comprises at leastin part saponifying esters and neutralizing organic acids contained inthe alcoholic product in the aldehyde column by adding thereto, in thealdehyde column, an alkaline rea-gent, the amount of alkaline reagentadded being insufficient to cause the bottom product from the aldehydecolumn, after the removal of low-boiling impurities, to have an alkalinereaction.

2. In a process for producing ethyl alcohol in which a beercontaining arelatively small proportion of alcohol is produced by fermentation anddistilled to produce an alcoholic product, the alcoholic product passedthrough an aldehyde column to remove low-boiling impurities, and thealcoholic liquor discharged from the aldehyde column is distilled andrectified Ain an alcohol still; the improvement which comprises at leastin part saponifying esters and neutralizing organicv acids contained inthe alcoholic product in the aldehyde column by adding thereto, in thealdehyde column, an alkaline reagent, the amount o1' alkaline reagentadded being such that the bottom product from the aldehyde column, afterthe removal of low-boiling impurities, has a slightly acid reaction.

3. In a process for producing ethyl alcohol in which a beer containing arelatively small proportion of alcohol is produced by fermentation anddistilled to produce an alcoholic product, the

alcoholic product passed through an aldehyde column to removelow-boiling impurities, and the alcoholic liquor discharged from thealdehyde column is distilled and rectied in an alcohol still; theimprovement which comprises at least in part saponifying esters andneutralizing organic acids contained in the alcoholic product in .thealdehyde column by adding thereto, in the column to remove low-boilingimpurities, and the alcoholic liquor dischargedfrom the aldehyde columnis distilled and rectiedin an alcohol still; the improvement whichcomprises at least in part saponifying esters and neutralizing organicacids contained in the alcoholic product in the aldehyde column byadding thereto. in the aldehyde column at a point where theconcentration oi esters is substantially the greatest, an alkalinereagent, the amount of alkaline reagent added being insuflicient tocause the bottom product from the aldehyde column, after the removal oflow-boiling impurities, to have an alkaline reaction.

5. In a process for producing ethyl alcohol in which a beer containing arelatively small proportion of alcohol is produced by fermentation anddistilled to produce an alcoholic product". 'the alcoholic productpassed through an aldehyde column to remove low-boiling impurities, andthe alcoholic liquor discharged from the aldehyde column is distilledand rectiiled in an alcohol still; the improvement which comprises atleast in part saponifying esters and neutralizing organic acidscontained in the alcoholic product in the aldehyde column by addingthereto, in the aldehyde column ata point where the concentration ofesters is substantially the greatest, sodium hydroxide, the amount of-sodium hydroxide added being such that the bottom product of thealdehyde column, after the removal of low-boiling impurities, has a pHof about 6.5.

LOUIS B. RODENBERG.

